Bad news, people. Predictable. Possibly inevitable. But no one wants to see the bad guys triumph. For the bigot on the bus made a clean getaway. You remember her, the white woman in her 30s who bellowed into her mobile phone that a "dirty fucking nigger" had taken her seat on the No 48 in central London. It wasn't her seat, but that's by the bye. She said what she said and, through shock, or fear, or indolence – perhaps a mixture of all three – a whole top deck of London bus passengers let her escape unchallenged. It doesn't change the price of coffee. But it's a shame.

Still, it was a close-run thing. A complaint was retrospectively made by a passenger called Alice. The bus company traced the bus, found the CCTV, found the bigot, or at least her image. "It is apparent that there is a comment made as the male passenger passes the female," officials said, but there was no sound. That's that. Well done Ms Potty Mouth. You win.

I find myself discussing it all with Cilius, an acquaintance who sits on the council of the Institute of Race Relations. He's a big guy and very much the interventionist. With him on the No 48, Ms Potty Mouth would not have got away so easily. Still, he understands how it can happen. "Sometimes people don't have time to think. Sometimes they know what's happening and disapprove but don't want the confrontation. When you confront someone, you also have to be ready for them to confront you back." Your potential interventionist, he says, is thinking all sorts of things: "Are they alone?" "Will anyone back me up?" Worse still, "Will people turn on me." Safer to sit still.

Isn't it all dispiriting, I suggest. Not really, says Cilius. Just a snapshot, albeit a nasty one. But instead, he says, you might focus on all those migrant deportation flights that don't take off because ordinary passengers object to the way that the deportees are being treated, or because pilots want no part of it when the process appears inhumane. Snapshots are just that and they can break the heart or lift the spirit. Good and bad. That's real life.